Parachutes failed to open as NASA's Genesis space capsule plunged back to Earth on Wednesday, causing it to take a tumble from the heavens and bury itself in the desert sands of western Utah, perhaps seriously damaging precious cargo revealing the origins of the solar system.

Scientists said the crash breached a canister containing more than 200 ceramic tiles inside the 450-pound capsule, exposing the principal payload to atmospheric contamination and probably reducing the tiles to a mishmash of shattered glass.

Nevertheless, experts said, solar particles embedded in the tiles may eventually be salvaged. "This is not the worst case -- the capsule could have crashed into a mountain," said Andrew Dantzler, director of NASA's solar system division. "There is still hope for a science result from this mission."

Helicopter stunt pilots waiting to pluck the parachuting Genesis out of the sky in a spectacular recovery instead watched helplessly as the discus-shaped capsule smashed into the ground at 193 mph and sank to its midsection in high desert of the Army's Dugway Proving Ground.

The two stunt helicopters and an accompanying Army Black Hawk helicopter landed at the crash site a few minutes later so experts could photograph the capsule, assess damage, and make plans for when and how to bring the craft to Dugway's Michael Army Air Field.

Chris Jones, director of solar system exploration at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said engineers had a plan to cope and late Wednesday brought the canister of tiles back to the airfield for disassembly in a special clean room.

The principal early concern was to disarm a mortar charge and five other pyrotechnic devices whose failure to explode -- possibly because of faulty batteries -- prevented Genesis's parachutes from deploying and led to the crash.

Roy Haggard, a member of the helicopter recovery team, said the capsule and a canister within had cracked open but "it was actually quite surprising how little damage there was."

Genesis was launched three years ago and spent 850 days with the tiles exposed to the solar wind to collect atoms representing all the elements and isotopes of the periodic table. The particles -- a few micrograms of the sun's primordial stuff -- were expected to tell scientists the composition of the solar system when it formed 4.5 billion years ago.

Regardless of the scientific outcome, the capsule's disastrous descent put a significant blemish on NASA's highly regarded unmanned space science program, which this year has had major successes with two Mars landers and the insertion of the Cassini spacecraft into orbit around Saturn.

The crash also raised questions about the prospects of NASA's new generation of "sample return" missions. Genesis was the first human-made vehicle to bring matter back from space since the moon missions of the 1970s, and it is to be followed by the reentry early next year of Stardust, which was sent to capture particles from a comet's tail, and eventually by a Mars sample return.

"The space business has humbled us," said Mars Exploration Program Manager Firouz Naderi. "We will be increasingly bringing samples back, and we will figure out what went wrong here and proceed."

For much of Wednesday, Genesis's success appeared assured. Shortly before 8 a.m. Eastern time, engineers announced that the capsule had been jettisoned from its parent spacecraft, reoriented itself with its heat shield facing Earth and increased its spin rate to keep it pointed properly for descent.

At 11:26 a.m., stunt pilots Cliff Fleming and Dan Rudert of South Coast Helicopters of Santa Ana, Calif., left Michael Air Field in their Eurocopter A-Stars to await Genesis's descent. They hovered 5,000 feet above a 23-by-15-mile elliptical target zone on the floor of Dugway's high desert. The sky was crystal clear.

Fleming's job was to snag the Genesis capsule by its rectangular parachute, called a parafoil, and lower it carefully to the ground to ensure the tiles were not damaged. He spent much of last week chasing the Batmobile through the streets of Chicago during the filming of "Batman 4," but he regarded the Genesis job as highly demanding because of the lack of visual reference points at high altitude.

The capsule hit its "keyhole" in Earth's atmosphere about 410,000 feet above the Pacific Ocean shortly before noon. At that point it was a fireball traveling at 24,861 mph -- with energy "like a 4.5 million-pound freight train traveling at 80 miles per hour" -- said Lockheed Martin's Bob Corwin, the capsule recovery team chief, in a briefing for reporters Tuesday.

At 11:58 a.m., cameras picked up the capsule as it crossed into U.S. airspace over northwest Oregon and passed over Idaho at 200,000 feet. Premature applause broke out in mission control at the Jet Propulsion Laboratory.

At this point, the remaining concerns were the two parachutes, a "drogue" designed to deploy at 108,000 feet to stabilize the capsule as it slowed in the upper atmosphere and the parafoil that was to unfurl at 22,000 feet. Fleming was poised to intercept the capsule and snatch the parafoil with an 18.5-foot gaff.

There was nothing to do but watch: "We had gone through each critical item and came to a conclusion that the thing ought to work," said Don Sevilla, leader of the payload recovery team. Once the final approach began, there was no way to tune or test the reentry mechanisms, he said.

As the capsule fell through the high atmosphere, it flickered oddly in the sun, and when it dropped lower, television viewers could see that it was tumbling because the drogue had not deployed, possibly because battery current had not exploded the mortar charge to release it.

With the Genesis team watching in silence, Genesis smacked into the landing zone edge first, sinking into the desert and coming to rest at a 10-degree angle from the perpendicular.

"I've been working on this project longer than anyone," said Genesis manager Don Sweetnam, who joined the team in 1997. "It's a difficult moment."

In an artist's rendering, Genesis's parachute releases properly, allowing a helicopter crew to snare the craft.